The language Opta used was fine. I understood that. What the metric calculates I’m fine with.
If you can explain how the formula calculates the metric please go ahead.
None of us work with Opta, so we wont know the exact formula.
What we do know is that they take into account a lot of factors including
the type of pass, was it cross, ground pass , headed pass etc,
the pattern of play, was it from open play, corner, throw in etc,
location of the receiver ..as in how far from goal the receiver is
lcoation of the passer ..as straight through ball or came from the side
distance of the pass itself... a longer pass would be harder to control than a 2 yard pass etc etc
After all these factors are taken into account, the rest is quite simple
For a certain type of pass from a certain location, with certain other factors, how often do goals get scored...out of how many. If they have counted 1000 goals scored from 2000 of a specific situation, it has an xG of 0.5 and the player who made the pass to create that xG gets that amount of xA.
Spurs consistently over perform on their xG not because of any coincidence . Its because Son and Kane are lethal motherfuckers. So the theory checks out.
Unless you believe Opta dont know how to deal with stats then, of course, thats another story.